1. Field
Exemplary embodiments of the present invention relate to a semiconductor design technology, and, more particularly, to an internal voltage generation circuit for generating an internal voltage that is temperature dependent.
2. Description of the Related Art
Generally, a semiconductor device such as a double data rate synchronous dynamic random access memory (DDR SDRAM) receives a power supply voltage from an external controller to generate an internal voltage used for various purposes. There are generally two methods for generating the internal voltage. One method generates the internal voltage by down-converting the power supply voltage, and the other method generates the internal voltage by pumping the power supply voltage.
Circuit size continues to decrease, and speed continues to increase as semiconductor technology develops. As integration and speed increase, the voltage level used in the circuit operation has to be lowered. Accordingly, technologies for stably generating, maintaining, and controlling low voltage levels are being studied at the present time.
The above technologies include research on circuits that generate an internal voltage that is dependent on temperature. Circuits that generate a temperature dependent internal voltage are generally designed by combining a circuit having a proportional to absolute temperature (PTAT) current characteristic and a circuit having a complementary to absolute temperature (CTAT) current characteristic. The PTAT current characteristic has a relationship where temperature is proportional to current, which means current increases as the temperature increases. The CTAT current characteristic has a relationship where temperature is inversely proportional to current, which means current decreases as temperature increases.
Circuits that generate a temperature dependent voltage are generally designed with a strong CTAT function and are sensitive to temperature, i.e. have large variations in voltage relative to temperature variation. However, to enlarge the CTAT current characteristic of the circuit, the current consumed in the circuit has to increase, and this causes a concern where the current consumed in the circuit exceeds a target current when the circuit operates.